Center



y 1933- D. A. GEGENHEIMER ET AL ,118,301

CENTER Filed Oct. 6, 1957 Invenzfons fleleri JZ 'eiqenfiez'rrzer Y Jam Jji r5 i @011 Patented May 24, 1938 CENTER Delbert A. Gegenheimer, Chicago, and James 1. Kirby, Oak Park, Ill.

application October 6, 1937,-Serial No. 167,580

14 Claims.

This invention relates to a center and particularly to a center so designed that it automatically and positively achieves a centering effect when a work piece is seated in it and thus achieves concentricity and avoids out'of balance and chatter" in the device in which it is used.

One object is to'provide a center 'for a lathe or other tool in which a work' piece may be readily and positively centered when being put into position for work and in which itfautomatically becomes centered even though the initial seating may be somewhat out of center, and in which it thereafter remains centered automatically by reason of the shape and construction of the centering device itself.

Anotherobject is to provide adevice of the type indicated which=may be readily removable to permit replacement and change.

Another object is to provide a device in which a special fixture to receive the end of an irregularly or unsymmetrically shaped work piece may be readily put in position in the device as a whole. V

Other objects will appear from time to time in 25 the course of the specificationand claims.

The invention is illustrated more or less diagrammatically in the accompanying drawing,

wherein: 1

Figure 1 is a longitudinal cross section illustrat- 30 ing one form of thedevice;

Figure 2 is an end view of the device of Figure 1;

Figure 3 is an elevation of the work receiving member of the device of Figures 1 and 2.

Figure 4 is a modified form of the work receiving member shown in elevation;

Figure 5 is a longitudinal sectionor a modified form of the work piece receiving member;

Figure 6 is an end elevation of the device of Figure 5; I

Figure 7 is a longitudinal section of a specially shaped work receiving member;

Figure 8 is an end elevation of the same showthe figure being takenon line 88 of Figure 7;

Figures 9 and 10 are generally similar to Figures 7 and 8 by illustrating a receiving membering a work piece in position partially in section,

Figure 11, with parts in section and parts in elevation; and i Figure 13 is a fragmentary longitudinal sectional view with parts broken away and parts in elevation showing a modification-0f the device of Figure 9.

Like parts are designated by like symbols throughout the specification and drawing.

I is the housing of a hollow and preferably tapered shank 2 which may beinteriorly threaded as at 3 to receive a rod 4 correspondingly threaded as .at 5 and slotted as at 6. The rod may be used to remove the work receiving assembly from the housing. For that purpose a tool such as the screw driver is inserted in the slot 6, the rod 4 rotated and forced inwardly to contact the work receiving member'to force it out. The housing includes a larger hollow section I which as shown has within it a raised annular portion 8 which extends somewhat above the floor or bottom 9 of the interior of the section I. The Wall of the section "I is perforated to receivea lubricating cup I0 which as shown has a spring ll tending normally to seat a ball l2 against the edges of a perforated member- I3, so that the ball normally stays in the closing position but may be readily pushed inwardly against the resistance of the spring to permit lubrication. Adjacent its outer edge, section I may have arr-inclined groove M in which a spring-ring l5 may be'seated. The spring ring serves to hold the parts within the section 1 against accidental displacement and may. be removed to permit disassembly of the device. I

There are seated within the hollow section 1 two bearings. There is thus a roller bearing comprising an outer race it which is positioned against. the inner surface of the outer wall of the section 1, and an inner race l'l. Tapered rollers I8 are positioned between the two races to contact them both. A ball bearing is positioned outwardly of the roller bearing and comprises an inner racel9 preferably in contact'with the inner race-ll of the roller bearing and an outer race 20 normally in contact with the inner surface of the section I. The races l9 and 20 are suitably shaped to receive the balls 2|. As shown, the inner races 17 and 19 have preferably the same interior diameter so that they readily receive the reduced shank 22 of the work piece receiving .member. This member is preferably providedwith an enlarged portion 23 which has conical depression 24 formed within it,' the walls of which are formed with an inclination of '30 degrees to the longitudinal axis of the device as 65 without proper centering. The arrangement of the roller bearing has been shown by experience to accomplish automatically the proper centering of the work piece holder 22, 23 within the assembly. The angularity of the races of the roller bearing is such that they accomplish this centering automatically and certainly. The combination of a roller, bearing with a ball bearing permits this because the ball bearings, being round,

set up no effective resistance to the'centering and permit that relatively minute movement or accommodation which is necessary to accomplish with certainty the centering.

In the modified form of the device shown in Figure 4, the shank 22 is the same as that shown in Figures 1 and 3, but instead of the depression a conical outwardly projecting member 26 is used. This type of center member or work piece receiving member is of particular advantagewhere the Work piece has a center already 'properly marked on it, as is sometimes the case. Then this center mark is positioned on the point 21 of the member 26.

In the further modification of Figure 5, the device is generally like that shown in Figure 3,

. but there are provided on the inner face of the conical depression 24 a plurality of raised lands or guides 28. The particular advantage of this construction is in connection with work piece which, while generally symmetrical, may have burrs" or other slight irregularities. The work piece may be so positioned that the burr or other irregularity does not contact one of the lands. 28 and is held out of contact with the inner face of the conical depression 24. Thus, even though the end of the work piece is irregular, proper centering may occur.

Where it is desired to use the device in connection with a work piece which is not symmetrical or not round, the work piece receiving member may be made up specially and given a particular shape to handle the desired work piece. Thus, as shown in Figures 7 and 8, the shank member 22, instead of having a symmetrical projection, such as the members 23 or 26, has a, projection. 29 which is generally rectangular as shown particularly in Figure 8 and' is provided with a depression 30 having inner faces 3| tapered inwardly preferably at the same inclination as that given to the inner faces of the conical depression 24. -The work piece is indicated as comprising a round portion 32 which is arranged co -axially with the portion 22 and having a non-round portion 33 received in. the depression 30 of the member 29. The shape of these parts serves to center the -portion,32 with respect to the work receiving device, and as in the case of the earlier forms the work receiving piece 22, 29 is centered by the bearings shown in Figure 1.

A further modified form indicated in tion is preferably the same as that of the walls That of Figure 1 is typical;

of the depression 24. There is shown seated in this member a workpiece having a section 31 which is co-axial with the stub portion 22. This work piece also carries two or more members 38 which are not co-axial with the section 31 or the stub 22.

There is shown in Figures 11 and 12 a further modified form in which the stub section 22 carries a work piece receiving member 39 which is generally elliptical as shown in Figure 12 and is hollow in its interior, the inner walls being preferably straightsided as at 40. The member 39 is split as at M. and terminates in a pair of perforated ears 42. The work piece having been inserted, maybe gripped by a bolt 43. In that form, the work piece comprises a section 44 co-' axial with the stub 22 and an elliptical section 45 which is not co-axial with that member.

Figure 13 illustrates a possible use of the forni of the device shownin Figures 11 and 12. As there shown, the device proper is that of the form shown in Figures 1, 2 and 3. The work holding piece is that shown in Figures 11 and 12.

It will be realized that whereas I have herewith shown and described a practical operative device, nevertheless many changes might be made in the size, shape, number and disposition of parts without departing from the spirit of the invention. In particular, the shape of the special fixtures shown in Figures 7 to 13, inclusive, might be almost indefinitely varied, and the combination of them, such as shown in Figure 13, might also be varied. While these fixtures in some sense and in some degree give a centering effect, the main centering is in all of the forms of the device accomplished by the arrangement of the antifriction bearings, and therefore the invention is not limited to any particularv arrangement of specific fixture or device to grip or to be adapted to the end or the particular shape of a work piece.

The use and operation of the invention are as follows:

The form of the device shown in Figure 1 may be considered as typical, although the work contacting piece of Figure 4 might be substituted for that of Figures 1, 2 and 3. Whatever the particular shape of the member or fixture which contacts the work, the operation of the device is generally'the same. as accurately as can be conveniently done on the fixture or piece which contacts it. The form shown in Figure 4 is particularly adapted for use where the work piece has a center marked on it. One example of such a use is in'connection with armatures in which the shaft frequently has a center definitely marked. Where that-is the case, the form of Figure 4 would be used and the point 21 engages the marking or depression which marks the center of the work piece. Where the center is not marked, ordinarily one of the other forms of work receiving pieces will be used:

Because of the in clination of the walls of the depression, the work piece is automatically, by the'mere act of penetration, brought into an approximate center position. The actual and final centering is accomplished automatically by the shape and arrangement ofthe bearings. The roller bearing particularly by reason of the inclination of its races, inevitably causes accurate centering of the portion 22. Should slight lateral tilting or adjust-.

ment be necessary, the ball bearings permit it, because their contact with their races is such as to permit some tilting or adjustment.

Therefore, the roller bearings accomplish a centering and the ball bearings cooperate with the rollerbearings to permit 'thiscenterlng. A plurality of roller bearings would ordinarily work against each other and one would tend to counteract the efiect of the other. I If a plur ty of ball bearings were used, they would, acco ing effect but will permit it to occur freely and at the same time will furnish adequate antifriction support for the member 22 and the part 23. v I

Where any of the special fixtures are to be a used, they are shaped to be adapted to the particular shape of the end of the work piece which they engage, and while rectangular, round an'd elliptical shapes have been shown, the invention is not illustrated to them and any shape at all might be used. It is preferable, although not necessary, to give the inner walls of these fixtures an inclination which is approximately the same as that of the depression 24 and thus furnishes to some degree a centering effect within the fixture itself. The form of Figure 11 does not accomplish a particular centering purpose but merely furnishes a means for gripping the enlarged and out of center end of the work piece so that the portion 22, which corresponds to the portion 22 'of Figure 1, may fit readily into the depression 24 for centering. I

The operation of the form of Figures and 6 is generally the same as that of Figures 1, 2 and 3, except that the raised portions 28 furnish a clearance so that if the end of the work piece should be slightly deformed or should be nicked or carries burrs or other projections, the work piece can be so positioned that these do not contact the raised members 28 and that those members contact only the undeformed portions of the end of the work piece, and thus proper centering ing toward the open side ofsaid enlargement,

1 and having its inner race engaging said center and its outer .race engaging the inner wall of said enlargement, and means for retaining said bearings in position.

2. In a tool center, a hollow housing member having an open-ended hollow enlargement, a center piece positioned therein for rotation with respect thereto, a roller bearing positioned within said'enlargement and about said center piece, having its inner race engaging said center-and its outer race engaging said enlargement, the

outer race being inclined-inwardly toward the axis of said housing at an angle of approximately thirty degrees with respect thereto, and a roller bearing positioned outwardly with respect to said roller bearing toward the open side of said enlargement, and having its'innerrace engaging said center and its outer race engaging the inner wall of said enlargement, and means for retaining said hearings in position.

3. In a tool center, a hollow housing member having an open-ended hollow enlargement, a center piece positioned therein for rotation with respect thereto, a roller bearing positioned within said enlargement and about said center piece, having its inner race engaging said center and its outer race engaging said enlargement, the outer race being inclined inwardly toward the axis of said housing, and a roller bearing positioned outwardly with respect to said roller bearing toward the open side of said enlargement, and having its inner race engaging said center and its outer race engaging the inner wall. of said enlargement, and means for retaining said bearings in position, said centering piece having a generally conical cavity formed in it, the sides of which incline inwardly at an angle of approximately 30 degrees with respect to the central axis of the center as a whole.

4. In a tool center, a hollow housing member having an open-ended -hollow enlargement, a center piece positioned therein for rotation with respect thereto, a roller bearing positioned within said enlargement and about said center piece, having its inner race-engaging said center and its outer race engaging said enlargement, the outer race being inclined inwardly toward the axis of said housing at an angle of approximately thirty degrees with respect thereto, and a roller bearing positioned outwardly with respect to said roller bearing toward the open side of said enlargement, and having its inner race engaging said center and its outer race engaging the inner wall of said enlargement, and means for retaining said bearings in position, said center piece having a generally conical cavity formed in it, the sides of which incline inwardly at an angle of approximately thirty degrees with respect to the central axis of the center as a whole.

5. Ina tool center, a hollow housing member having an open-ended hollow enlargement, a

- center piece positioned therein for rotation with respect thereto, a roller bearing positioned within said enlargement and about said center piece, having its inner race engaging said center and its outer race engaging said enlargement, the outer race being inclined inwardly toward the axis of said housing, and a roller bearing positioned outwardly with respect to said roller bearing toward the open side of said enlargement, and hav- 'ing its inner race engagingsaid center and its outer race engaging the inner wall of said enlargement, and means for retaining said hearings in position, said center piece having a generally conical depression and a plurality of raised lands formed in its inner wall and converging toward its center.

6. ha tool center, a hollow housing member having an open-ended hollow enlargement, a center piece positioned therein for rotation with re- ,spect thereto, a roller bearing positioned within said enlargement and about said center piece,

having a generally conical depression and a plurality of raised lands" formed in its inner wall and converging toward its center.

'7. A center piece for tools comprising a member having a cavity generally conical and means within said cavity for centering-a work piece, said means comprising a plurality of raised lands" lying within the cavity and converging toward its center, said lands comprising the seating surface member and a hollow open-ended enlargement, a,

center piece positioned for rotation within said enlargement and a plurality of anti-friction bearings positioned within said enlargement and supporting said center, the bearings comprising a roller bearing and a ball bearing, each arranged with its inner race contacting the center and its outer race contacting the inner wall of the enlargemnt, the ball bearing being positioned outwardly toward the open end of the enlargement beyond the roller bearing.

10. In combination in a tool center, an elongated member and an integral hollow openended enlargement, a center piece positioned for rotation within said enlargement and a plurality of anti-friction bearings positioned within said enlargement and supporting said center, the bearings comprising a roller bearing and a ball bearing, each arranged with its inner race contacting the center and its outer race contacting the inner wall of the enlargement, the ball bearing being positioned outwardly toward the open end of the enlargement beyond the roller bearing.

11. In combination in a tool center, an elongated member and an integral hollow openended enlargement, a center piece positioned for rotation within said enlargement and a plurality of anti-friction bearings positioned within said enlargement and supporting said center, the bearings comprising a roller bearing and a ball bearing, each arranged with its inner race contactingthe center and its outer race contacting the inner wall of the enlargement, the ball bearing being positioned outwardly toward the open end of the enlargement beyond the roller bearing, the outer race of the roller bearing being inclined inwardly toward the axis of the center as a whole at an angle of approximately 30 degrees to the line of the axis of the apparatus. 4

12. A center piece for tools comprising a member having a generally rounded shank and a cavity opening away from said shank and out of center with respect to said shank, the walls of said cavity tapering inwardly at an angle of approximately 30 degrees with respect to the axis of said shank.

13. A center piece for tools comprising a. member having a generally rounded shank and a cavity opening away from said shank, the walls of said cavity tapering inwardly at an angle of approximately 30 degrees with respect to the axis of said shank, said cavity being of generally rectangular cross section.

14. A center piece for tools comprising a member having a generally rounded shank and a cavity opening away from .said shank, the walls of said cavity tapering inwardly at an angle of approximately 30 degrees with respect to the axis of said shank, said cavity being of generally elliptical cross section.

DELBERT A. GEGENHEIMER. JAMES J. KIRBY. 

